With the explosion in communication via the Internet in recent years, there has been a corresponding increase in demand for high bandwidth networks, such as networks incorporating optical fibers. One type of network architecture includes several different classes or types of networks coupled together to enable users to communicate with each other. Enterprise or access level networks provide bandwidth to individual customers and typically connect to larger metropolitan level networks. The metropolitan level networks, in turn, typically connect to even larger long haul or backbone level networks. In one type of network topology, each network is configured as a ring, with each ring having a number of nodes configured to add or drop traffic to or from the parent network.
In conventional metropolitan level ring networks (often referred to as metropolitan area networks or MANs), carrier level switching facilities receive traffic from the long haul network and distribute the traffic among a number of carrier aggregation facilities using Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) frames delivered via time domain multiplexing (TDM) technologies. Each aggregation facility connects to an access level network for delivering the SONET/SDH frames to customer premises.
Unfortunately, TDM aggregation and processing equipment is costly and difficult to maintain. Each aggregation point on a traditional SONET over TDM network requires significant infrastructure development. Additionally, switching systems associated with SONET frames delivered via TDM require costly traffic grooming and other equipment at the enterprise or local network level. Lastly, the optical-to-digital and digital-to-optical conversions required to process TDM signals introduce additional cost and potential errors at the aggregation facilities and customer premises locations.